Mobile communication terminals use rechargeable batteries that only last for a predetermined duration. However, mobile communication terminals are used on a daily basis during all hours of the day and thus will run out of battery unless the battery is regularly charged. Thus, it is desirable to control battery power consumption in a mobile communication terminal.
Battery consumption can be minimized by maximizing the standby time of the mobile communication terminal. By setting an index value according to a time zone in a slot cycle (i.e., a slot mode of the mobile communication terminal), the slot cycle is changed by adjusting a slot cycle index (SCI) value in the mobile communication terminal. To adjust a power-saving mode of the mobile communication terminal, a base station for the mobile communication terminal does not adjust its slot cycle.
So, the slot cycle of the mobile communication terminal becomes greater than that of the base station. Hence, a paging message sent from the base station may not be received by the mobile communication terminal.
In particular, when an SCI value between a mobile communication terminal and a base station is set to ‘2’, monitoring time between the mobile communication terminal and the base station is performed each slot cycle of 5.12 seconds. Accordingly:‘Slot cycle length=1.28*2i, where ‘i’ is a slot cycle index’  (Equation 1)
According to Equation 1, if the SCI value set in the mobile communication terminal is adjusted by ‘3’ to enter the power-saving mode of the mobile communication terminal, the adjusted slot cycle of the mobile communication terminal becomes 10.24 seconds.
Yet, since the base station keeps the initial SCI value of ‘2’ without adjusting to SCI of the mobile communication terminal, the base station will perform the monitoring with the slot cycle of 5.12 seconds.
Accordingly, the mobile communication terminal, as shown in FIG. 1, wakes up from the power-saving mode at slot cycles t0, t2 or t4, while the base station monitors slot cycles of t0, t1, t2, t3 or t4. Thus, the mobile communication terminal and the base station differ from each other in slot cycle.
Paging messages sent from the mobile communication terminal to the base station can be monitored by the base station without loss. However, in case of paging messages sent from the base station, since the slot cycle of the mobile communication terminal is elongated, the paging message sent for the slot cycle t1 or t3 is lost because the mobile communication terminal is in standby mode in those cycles.
A system or method is needed to overcome the above problem.